Question about 2004 Chevrolet TrailBlazer

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Ambient sensor gauge stopped working correctly at the same time the AC quit

AC Clutch doesn't engage and the ambient sensor shows the outside temp to be 25 deg cooler than what it really is (75 instead of the actual temp of 99). Both seemed to happen at the same time. Could they be related ? Should I try resetting the ambient sensor by disconnecting the cables from the battery and holding them together for 15 min or is there another way ? Thanks

Posted by Terry on

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  • Terry Jul 25, 2012

    Need to add the car has died sitting at a stop light twice since this started

  • Terry Jul 25, 2012

    Just noticed that the compass reading is wrong now to. WTH ?

  • Terry Jul 25, 2012

    Thank you Freddy. I reset the ECM by holding + & - batt cables together for 30 min. The compressor now comes on and the ambient sensor is showing the correct outside temp. I will tackle the throttle body cleaning this weekend



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  • Chevrolet Master
  • 1,311 Answers

The ambient temp sensor is related to the AC function, if the HVAC system thinks the outside temp is too low, the AC will not be turned on. You probably have a defective temp. sensor. It is easy to change and relatively inexpensive. It is located on the underside of the top radiator support almost in the center (just to the drivers side of center).
The car dying at a stop light can probably be solved by cleaning the throttle body. Make sure that both the front and rear sides of the throttle body are cleaned. And also disconnect the battery during the cleaning process, this will reset the computer and allow it to relearn to the cleaned throttle body.
The compass issue is another separate issue and may just require a recalibration. I don't know what the procedure is but try Googling the subject.

Posted on Jul 25, 2012


5 Related Answers


Harvey N Tawatao

  • 3854 Answers

SOURCE: eng. code P1484

P1484 - Cooling Fan System Performance

06-06-2005, 10:51 PMHere's what the GM Manual says about this code:

The cooling fan relay sends a pulse width modulation (PWM) signal of 12-14 volts to the cooling fan clutch through the cooling fan clutch supply voltage circuit. The powertrain control module (PCM) uses this PWM signal in order to control the speed of the cooling fan clutch. The signal controls the position of the oil control valve inside the cooling fan clutch. If the cooling fan RPM is different than the PCM is expecting, DTC P1484 will set. The actual cooling fan RPM vs the desired cooling fan RPM is not always exactly the same. There can be up to an 800-RPM difference.

The engine is running.
The system voltage is greater than 8.5 volts.
The intake air temperature (IAT) is greater than -7°C (19°F).
DTCs P1481 and P1482 are not set.
The engine speed is less than 3200 RPM.
The engine speed is not changing more than 250 RPM for 5 seconds.
Fan command is greater than 0%.

The maximum allowable error of 1000 RPM in the cooling fan speed occurs for 100 seconds.
The PCM detects that the cooling fan clutch is locked up.

The Reduced Engine Power indicator illuminates only if the PCM detects that the cooling fan clutch is locked up.
The PCM illuminates the malfunction indicator lamp (MIL) during the second consecutive trip in which the diagnostic test has been run and failed.
The PCM will store the conditions as Freeze Frame/Failure Records data.
The PCM commands the cooling fan clutch to 100%.

Follow this procedure in order to clear DTC P1484 after completing a repair.

Use the Clear DTC Information function on the scan tool.
Perform an ignition key cycle.
The PCM turns OFF the MIL after the third consecutive trip that the diagnostic test has run and passed.

The history DTC will clear after 40 consecutive warm-up cycles have occurred without a malfunction.

An inline connector could cause an intermittent DTC. Ensure to test for poor connections and pin retention at all inline connectors. Refer to system schematics for connector and locations.
If the condition is not present, refer to Testing for Intermittent and Poor Connections in Wiring Systems.

Disconnect the harness connector of the cooling fan clutch from the shroud. Inspect the exposed wires between the harness connector and the tubing.
If DTCs P1484 and P0113 are set, and the weather conditions are cold, the cooling fan code may be false. Clear DTC P1484, and after an IAT sensor check, allow the DTC to reset .

I'd say that 'fan clutch is faulty' is your problem, based on the information you gave. Thank you for using Fixya and good luck

Posted on Jul 10, 2010


gerald darling

  • 353 Answers

SOURCE: 91 chevy 1500 ac light flashing

try disconnecting the negative battery cable for ten minutes to reset the computer.

good luck

Posted on Jun 24, 2009

Jonah Oneal

  • 14092 Answers

SOURCE: i have a 99 chevy suburban 1500 V8 5.7L vin R and

problem could be in your AC and HEATER control switch.

Posted on Jul 04, 2009

chris quammen

  • 811 Answers

SOURCE: Instrument gauges quit working

run scanner for trouble codes, some auto parts stores will do this for free

Posted on Sep 27, 2009

Testimonial: "Thanks for the help i have yet to run it by to a parts store to check codes , just frustrating having a low milage car and the gauges go wacky. "


  • 41 Answers

SOURCE: all my gauges quit working at same time. fuses seem ok.

replace instrument panel cluster if power and ground ok ground wire at rear of engine behind intake manifole gm special policy warrenty coverage for up to 80000 miles

Posted on Nov 27, 2009

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